In the field of magnetic disk storage apparatuses (hereinafter sometimes referred to as disk drives) represented by hard disk drives, techniques for perpendicular magnetic recording and high-frequency assisted writing have been developed to facilitate an increase in recording density and recording capacity.
High-frequency assisted recording is a recording scheme in which a magnetic head with a high-frequency assisted element is used to apply a high-frequency magnetic field onto a magnetic disk. As a high-frequency assisted element, for example, a spin-torque oscillator (hereinafter sometimes referred to as an STO) has been gathering attention. The disk drive generates a high-frequency magnetic field by passing a DC current through the STO via an electrode to drive the STO so that the STO works as a source of oscillation.
The conventional disk drive with the magnetic head incorporated therein and comprising the high-frequency assisted element has no function to determine the level of possible oscillation degradation in the high-frequency assisted element. Thus, repeated recording operations of the magnetic head may make destruction of the high-frequency assisted element progress. When the high-frequency assisted element is destroyed, contaminant may be generated in the drive. The contaminant is fine dust or the like and may cause the magnetic head to crash on the magnetic disk. In this case, rescuing data on the magnetic disk corrupted by the head crash is difficult. Furthermore, the disk drive may be likely to fail to operate normally.